The invention relates broadly to a system for controlling the condition of air in a duct. More specifically, the invention pertains to a control system which senses the condition of air in a duct to regulate that condition. The condition can be velocity, static pressure or the like.
In controlling a condition of a space, for example temperature, dampers are sometimes used to regulate the amount of conditioned air supplied to one or more zones. The damper is regulated by a sensor, such as a thermostat. If there are a plurality of zones involved, a damper is positioned to control the amount of air supplied individually to each zone and each damper has a different position depending upon the temperature or condition of its associated zone. As the condition in each zone changes, the position of the damper changes which results in a variation in pressure and volume of air delivered by the ducts to the zones. This variation in pressure and volume of air delivered to the zones affects the speed of response of the system.
In order to eliminate this problem, known prior art systems have used static pressure sensors to adjust the position of the damper to maintain the static pressure in the duct constant. These known systems have, however, required the use of complex and expensive control systems.